Particular combustion systems for gas turbine engines utilize combustors having bundled tube type fuel nozzles for premixing a gaseous fuel with a compressed air upstream from a combustion zone. A bundled tube type fuel nozzle assembly generally includes a tube bundled including multiple tubes that extend through a fuel plenum body which is at least partially defined by a forward plate, an aft plate and an outer band that extends between the forward plate and the aft plate. Each tube includes an inlet defined at or upstream from the forward plate and an outlet defined at or downstream from the aft plate. During operation, compressed air flows into the inlet of each tube. Fuel from the fuel plenum is injected into one or more of the tubes where it premixes with the compressed air. The premixed fuel and compressed air is then routed into the combustion zone.
Fuel is provided to the fuel plenum via an annular fluid conduit which is fluidly coupled to a round opening defined in the forward plate. The tubes of the tube bundle are annularly arranged around the round opening to accommodate the fluid conduit. Because the tubes are straight or extend linearly from the inlet to the outlet, a corresponding round blank or bluff area is formed at the aft plate which may be challenging to cool during operation. In addition, the fluid conduit reduces the total number of tubes of the tube bundle which may result in non-uniform fuel distribution from the fuel nozzle assembly to the combustion zone.